Data processing method, apparatus, and system

ABSTRACT

A data processing method by a data sending apparatus is described. The method includes receiving a data packet from a PDCP layer, where the data packet is used as an RLC SDU. The method further includes encapsulating the RLC SDU into at least one RLC PDU, where each one of the at least one RLC PDU includes a header and a payload. The payload carries data from a single RLC SDU. It can be learned that a transmit end no longer performs concatenation processing at the RLC layer on the data packet. In this way, concatenation processing at the transmit end is reduced, and processing complexity and processing latency are further reduced. In addition, processing at a receive end also becomes simpler and more efficient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2017/105044, filed on Sep. 30, 2017, which claims priority toChinese Patent Application No. 201610873599.9, filed on Sep. 30, 2016.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a data processing method, apparatus, and system.

BACKGROUND

With development of wireless communications technologies, performance,such as a peak rate and system bandwidth, of a wireless network isimproved continuously, and service experience brought to users isgetting better and better. Therefore, wireless communication gainsincreasingly wider application. Expansion of the application of wirelesscommunication brings more service data to the wireless network.Therefore, higher requirements are raised for data processing efficiencyof a data transmit end and a data receive end.

SUMMARY

In view of this, this application provides a data processing method,apparatus, and system, so as to improve data processing efficiency.

According to a first aspect, a data processing method is provided. Themethod is performed by a data sending apparatus and includes thefollowing steps: receiving a data packet from a Packet Data ConvergenceProtocol (PDCP) layer, where the data packet is used as a Radio LinkControl (RLC) service data unit (SDU); and encapsulating the RLC SDUinto at least one RLC protocol data unit (PDU), where each the RLC PDUencapsulated at an RLC layer by the data sending apparatus includes aheader and a payload, and the payload is used to carry data from asingle RLC SDU.

According to a second aspect, a data processing apparatus is provided,located at a transmit end and including means or units configured toperform the steps in the first aspect.

According to a third aspect, a data processing apparatus is provided,including a processor and a memory. The memory is configured to store aprogram, and the processor invokes the program stored in the memory, toperform the method provided in the first aspect of this application.

According to a fourth aspect, this application provides a dataprocessing apparatus, including at least one processing element (orchip) configured to perform the method in the first aspect.

According to a fifth aspect, this application provides a program. Theprogram is used to perform the method in the first aspect when beingexecuted by a processor.

According to a sixth aspect, a program product is provided, for example,a computer readable storage medium, including the program in the fifthaspect.

According to a seventh aspect, a data processing method is provided. Themethod is performed by a data receiving apparatus and includes thefollowing steps: receiving, at an RLC layer, a data packet from a MAClayer, where the data packet includes an RLC PDU, the RLC PDU includes aheader and a payload, and the payload is used to carry data from asingle RLC SDU; and when determining, based on the header of the RLCPDU, that the payload of the RLC PDU is a complete RLC SDU, obtainingthe RLC SDU, and sending the RLC SDU to a PDCP layer; and/or whendetermining, based on the header of the RLC PDU, that the payload of theRLC PDU is a segment of an RLC SDU, obtaining all segments of the RLCSDU, restoring all the segments to the RLC SDU, and sending the RLC SDUto a PDCP layer.

According to an eighth aspect, a data processing apparatus is provided,located at a receive end and including means or units configured toperform the steps in the seventh aspect.

According to a ninth aspect, a data processing apparatus is provided,including a processor and a memory. The memory is configured to store aprogram, and the processor invokes the program stored in the memory, toperform the method provided in the seventh aspect of this application.

According to a tenth aspect, this application provides a data processingapparatus, including at least one processing element (or chip)configured to perform the method in the seventh aspect.

According to an eleventh aspect, this application provides a program.The program is used to perform the method in the seventh aspect whenbeing executed by a processor.

According to a twelfth aspect, a program product is provided, forexample, a computer readable storage medium, including the program inthe eleventh aspect.

In the foregoing aspects, that the payload of the RLC PDU is used tocarry data from a single RLC SDU means that even if the RLC PDU canaccommodate more than one RLC SDU or more than one segment of an RLCSDU, a payload of each the RLC PDU is used to carry only data from asingle RLC SDU. In other words, the data sending apparatus does notperform concatenation processing at the RLC layer on data packets.

It can be learned that in a process where the data sending apparatusencapsulates, at the RLC layer, the RLC SDU into the RLC PDU, thepayload of each assembled RLC PDU is used to carry the data from asingle RLC SDU. In other words, the payload of the RLC PDU does notinclude data of another RLC SDU. That is, the data sending apparatus nolonger performs concatenation processing at the RLC layer on RLC SDUs.In this way, concatenation processing at the transmit end can bereduced, and processing complexity and processing latency can bereduced.

In addition, the receive end may reorder, at the RLC layer, segments ofa single RLC SDU only, without a need to reorder RLC SDUs. Therefore,processing at the receive end can be simplified, and processingcomplexity and processing latency at the receive end can be reduced.

In the foregoing aspects, the header of the RLC PDU includes a segmentindicator (SI) field, used to indicate what is encapsulated into the RLCPDU where the SI field is located is a complete RLC SDU or a segment ofan RLC SDU.

Optionally, the SI field includes two bits, and values of the SI fieldare described as follows:

a first value is used to indicate that what is encapsulated into the RLCPDU where the SI field is located is a complete RLC SDU, a second valueis used to indicate that what is encapsulated into the RLC PDU where theSI field is located is a first segment of an RLC SDU, a third value isused to indicate that what is encapsulated into the RLC PDU where the SIfield is located is a middle segment of an RLC SDU, and a fourth valueis used to indicate that what is encapsulated into the RLC PDU where theSI field is located is a last segment of an RLC SDU; or

a first value is used to indicate that what is encapsulated into the RLCPDU where the SI field is located is a complete RLC SDU, and a secondvalue is used to indicate that what is encapsulated into the RLC PDUwhere the SI field is located is a last segment of an RLC SDU.

Optionally, the SI field includes one bit, and values of the SI fieldare described as follows:

a first value is used to indicate that what is encapsulated into the RLCPDU where the SI field is located is a complete RLC SDU or indicate thatwhat is encapsulated into the RLC PDU where the SI field is located is alast segment of an RLC SDU, and a second value is used to indicate thatwhat is encapsulated into the RLC PDU where the SI field is located is afirst segment or a middle segment of an RLC SDU.

In the foregoing aspects, the header of the RLC PDU further includes asegment offset (SO) field, used to indicate a byte offset, of a firstbyte in a payload of the RLC PDU where the SO field is located, withinan RLC SDU to which the payload belongs.

In the foregoing aspects, the header of the RLC PDU further includes asequence number (SN) field, and when one RLC SDU is encapsulated into aplurality of RLC PDUs, SNs in SN fields in headers of the plurality ofRLC PDUs are the same.

Optionally, the SN field may be used to indicate an RLC SDU to whichdata transmitted in the RLC PDU where the SN field is located belongs.

Optionally, an SN in the SN field is configured by the PDCP layer.

In the foregoing aspects, the header of the RLC PDU further includes alength indicator (LI) field, used to indicate a length of a payload inthe RLC PDU where the LI field is located.

In the foregoing aspects, the header of the RLC PDU further includes adata/control field, used to indicate whether a data packet or a controlpacket is transmitted in the RLC PDU where the data/control field islocated.

In the first aspect to the sixth aspect, a process where the datasending apparatus encapsulates the RLC SDU into at least one RLC PDUincludes: encapsulating the RLC SDU into the at least one RLC PDU basedon an indication from a MAC layer; or encapsulating the RLC SDU into theat least one RLC PDU based on a preset RLC PDU size. Correspondingly, aunit that encapsulates the RLC SDU into the at least one RLC PDU isconfigured to: encapsulate the RLC SDU into the at least one RLC PDUbased on the indication from the MAC layer; or encapsulate the RLC SDUinto the at least one RLC PDU based on the preset RLC PDU size.

In the first aspect to the sixth aspect, the data sending apparatus mayfurther send an RLC data packet to the MAC layer. The RLC data packetincludes one or more RLC PDUs. Correspondingly, the data processingapparatus further includes a unit that performs this step.

In the first aspect to the sixth aspect, the data sending apparatus usesthe RLC data packet as a MAC SDU and encapsulates the MAC SDU into a MACPDU. The MAC PDU includes a MAC header and a MAC payload, the MAC headerincludes at least one subheader, each subheader corresponds to onelogical channel, the subheader includes a first extension field and asecond extension field, the first extension field is used to indicatewhether the MAC PDU further includes another subheader or furtherincludes data of another logical channel, and the second extension fieldis used to indicate whether the MAC PDU further includes other data of alogical channel corresponding to a subheader where the second extensionfield is located. Correspondingly, the data processing apparatus furtherincludes a unit that performs this step.

In the seventh aspect to the twelfth aspect, when the RLC SDU sent tothe PDCP layer does not include a PDCP sequence number, the datareceiving apparatus sends the SN in the SN field to the PDCP layer. ThePDCP sequence number is a sequence number allocated to the PDCP PDU whenthe transmit end assembles the PDCP PDU.

In the seventh aspect to the twelfth aspect, when the RLC data packetincludes a plurality of RLC PDUs, the data receiving apparatus maydistinguish between the RLC PDUs based on the LI field.

In the seventh aspect to the twelfth aspect, when the RLC layer uses anunacknowledged mode (UM), the data receiving apparatus maintains, at theRLC layer, a reordering window, and the data processing method furtherincludes: when a first RLC PDU is out of the reordering window and thefirst RLC PDU includes a segment of an RLC SDU that fails to bereassembled, discarding, by the data receiving apparatus, all receivedRLC PDUs corresponding to the RLC SDU that fails to be reassembled.Correspondingly, the data processing apparatus further includes a unitconfigured to perform this step.

Optionally, the data receiving apparatus may notify the PDCP layer ofthe discarded RLC SDU. Correspondingly, the data processing apparatusfurther includes a unit configured to perform this step.

In the seventh aspect to the twelfth aspect, when SNs of received RLCPDUs are discontinuous, the data receiving apparatus starts a timer at afirst discontinuous position. The timer may be referred to as anassociated timer. Before the timer expires, when RLC PDUs that includemissing SNs are received, the data receiving apparatus stops the timer.When the timer expires, that is, RLC PDUs that include missing SNs arenot received before the timer expires, the data receiving apparatusmoves a lower edge of the reordering window to a position of an SNcorresponding to the first discontinuous position, namely, a position ofan SN corresponding to a first RLC SDU that is not delivered to an upperlayer. The SN is referred to as a first SN.

Optionally, the data receiving apparatus discards an RLC PDU that is notdelivered to the PDCP layer and whose SN is before the first SN.Further, optionally, the data receiving apparatus notifies the PDCPlayer of an SN of an RLC SDU corresponding to the discarded RLC PDU.

In the seventh aspect to the twelfth aspect, before the receiving, by adata receiving apparatus, a data packet from a MAC layer, the methodfurther includes: obtaining, at the MAC layer, a MAC SDU based on aformat of a MAC PDU, and using the MAC SDU as the data packet sent tothe RLC layer. The format of the MAC PDU is as follows:

The MAC PDU includes a MAC header and a MAC payload, the MAC headerincludes at least one subheader, each subheader corresponds to onelogical channel, the subheader includes a first extension field and asecond extension field, the first extension field is used to indicatewhether the MAC PDU further includes another subheader or furtherincludes data of another logical channel, and the second extension fieldis used to indicate whether the MAC PDU further includes other data of alogical channel corresponding to a subheader where the second extensionfield is located.

According to a thirteenth aspect, an RLC PDU structure is provided. TheRLC PDU includes a header and a payload, and the payload is used tocarry data from a single RLC SDU.

The header of the RLC PDU is the same as that in the foregoingdescriptions.

According to a fourteenth aspect, a data processing method is provided.The method is performed by a data sending apparatus and includes thefollowing steps: receiving an RLC data packet from an RLC layer, wherethe RLC data packet includes at least one RLC PDU; and using the RLCdata packet as a MAC SDU and encapsulating the MAC SDU into a MAC PDU,where the MAC PDU includes a MAC header and a MAC payload, the MACheader includes at least one subheader, each subheader corresponds toone logical channel, the subheader includes a first extension field (Efield) and a second extension field (H field), the first extension fieldis used to indicate whether the MAC PDU further includes anothersubheader or further includes data of another logical channel, and thesecond extension field is used to indicate whether the MAC PDU furtherincludes other data of a logical channel corresponding to a subheaderwhere the second extension field is located.

According to a fifteenth aspect, a data processing method is provided.The method is performed by a data receiving apparatus and includes thefollowing steps: receiving a MAC PDU from a PDCP layer; obtaining a MACSDU based on a format of the MAC PDU; and sending the MAC SDU to an RLClayer. The format of the MAC PDU is as follows: The MAC PDU includes aMAC header and a MAC payload, the MAC header includes at least onesubheader, each subheader corresponds to one logical channel, thesubheader includes a first extension field (E field) and a secondextension field (H field), the first extension field is used to indicatewhether the MAC PDU further includes another subheader or furtherincludes data of another logical channel, and the second extension fieldis used to indicate whether the MAC PDU further includes other data of alogical channel corresponding to a subheader where the second extensionfield is located.

According to a sixteenth aspect, a data processing apparatus isprovided, located at a transmit end and including means or unitsconfigured to perform the steps in the fourteenth aspect. Alternatively,a data processing apparatus is provided, located at a receive end andincluding means or units configured to perform the steps in thefifteenth aspect.

According to a seventeenth aspect, a data processing apparatus isprovided, located at a transmit end and including a processor and amemory. The memory is configured to store a program, and the processorinvokes the program stored in the memory, to perform the method providedin the fourteenth aspect of this application. Alternatively, a dataprocessing apparatus is provided, located at a receive end and includinga processor and a memory. The memory is configured to store a program,and the processor invokes the program stored in the memory, to performthe method provided in the fifteenth aspect of this application.

According to an eighteenth aspect, this application provides a dataprocessing apparatus, located at a transmit end and including at leastone processing element (or chip) configured to perform the method in thefourteenth aspect. Alternatively, this application provides a dataprocessing apparatus, located at a receive end and including at leastone processing element (or chip) configured to perform the method in thefifteenth aspect.

According to a nineteenth aspect, this application provides a program.The program is used to perform the method in the fourteenth aspect orthe fifteenth aspect when being executed by a processor.

According to a twentieth aspect, a program product is provided, forexample, a computer readable storage medium, including the program inthe nineteenth aspect.

It can be learned that in the foregoing solutions, only one LCD isneeded to indicate data of a single logical channel. Therefore, headeroverheads at the MAC layer can be effectively reduced.

In the foregoing aspects, the subheader of the MAC PDU further includesa logical channel identifier (LCD) field, used to indicate a logicalchannel to which a payload associated with the subheader belongs.

In the foregoing aspects, the subheader of the MAC PDU further includesa first length indicator field (F field) and a second length indicatorfield (L field). The first length indicator field is used to indicate alength of the second length indicator field, and the second lengthindicator field is used to indicate a length of a payload associatedwith the subheader where the second length indicator field is located.

According to a twenty-first aspect, a data processing method isprovided. The method is used on a data sending apparatus, the datasending apparatus maintains, at a PDCP layer, a PDCP transmit window,and the method includes: sending, at the PDCP layer by the data sendingapparatus, PDCP PDUs to an RLC layer; and when a quantity of the sentPDCP PDUs reaches a maximum quantity of PDCP PDUs that can beaccommodated by the PDCP transmit window, and the data sending apparatusdoes not receive a successful feedback at the PDCP layer, stopping, bythe data sending apparatus, sending a PDCP PDU. The success feedback isa status report fed back at the RLC layer by the data sending apparatus,indicating that all or some PDCP PDUs are successfully sent, or thesuccess feedback is a status report fed back by a data receivingapparatus, indicating that all or some PDCP PDUs are successfullyreceived.

According to a twenty-second aspect, a data processing apparatus isprovided, located at a transmit end and including means or unitsconfigured to perform the steps in the twenty-first aspect.

According to a twenty-third aspect, a data processing apparatus isprovided, including a processor and a memory. The memory is configuredto store a program, and the processor invokes the program stored in thememory, to perform the method provided in the twenty-first aspect ofthis application.

According to a twenty-fourth aspect, this application provides a dataprocessing apparatus, including at least one processing element (orchip) configured to perform the method in the twenty-first aspect.

According to a twenty-fifth aspect, this application provides a program.The program is used to perform the method in the twenty-first aspectwhen being executed by a processor.

According to a twenty-sixth aspect, a program product is provided, forexample, a computer readable storage medium, including the program inthe twenty-fifth aspect.

It can be learned that the transmit end may maintain, at the PDCP layer,a PDCP transmit window, to control data packet sending at the PDCPlayer. This can effectively reduce a problem that PDCP SNs are repeatedwhen an amount of data sent by the transmit end exceeds a range of datathat can be indicated by the PDCP SN, thereby resolving a problem that areceive end cannot correctly distinguish and process a plurality of datapackets that have same SNs and that are received at the PDCP layer.

In the foregoing aspects, a size of the PDCP transmit window isdetermined based on a PDCP sequence number or is preset.

Further, the size of the PDCP transmit window is determined based on thefollowing formula: W=(L+1)/2, where W denotes the size of the PDCPtransmit window, and L denotes a value of a maximum sequence number thatcan be indicated by a length of the PDCP sequence number.

In the foregoing aspects, the data sending apparatus sends, at the PDCPlayer, the PDCP sequence number to the RLC layer. The PDCP PDU carriesthe PDCP sequence number, or the PDCP sequence number is independent ofthe PDCP PDU. The PDCP sequence number is a sequence number allocated tothe PDCP PDU when the data sending apparatus assembles the PDCP PDU.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a communication scenario according toan embodiment of this application;

FIG. 2 is a schematic diagram of a user plane protocol stack followed bycommunication between a terminal and a RAN device according to anembodiment of this application;

FIG. 3 is a schematic diagram of a data processing method according toan embodiment of this application;

FIG. 4 is a schematic diagram of a format of an RLC PDU according to anembodiment of this application;

FIG. 5 is a schematic diagram of another format of an RLC PDU accordingto an embodiment of this application;

FIG. 6 is a schematic diagram of an RLC data packet according to anembodiment of this application;

FIG. 7 is a flowchart of a data processing method according to anembodiment of this application;

FIG. 8 is a schematic structural diagram of an existing MAC PDU;

FIG. 9 is a schematic structural diagram of a MAC PDU according to anembodiment of this application;

FIG. 10 is a schematic structural diagram of a data processing apparatusaccording to an embodiment of this application;

FIG. 11 is a schematic structural diagram of a data processing apparatusaccording to an embodiment of this application;

FIG. 12 is a schematic structural diagram of a data processing apparatusaccording to an embodiment of this application;

FIG. 13 is a schematic structural diagram of a terminal according to anembodiment of this application;

FIG. 14 is a schematic structural diagram of a RAN device according toan embodiment of this application;

FIG. 15 is a schematic diagram of a method for configuring a measurementgap parameter according to an embodiment of this application; and

FIG. 16 is a schematic diagram of a method for configuring a measurementgap parameter according to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of this application with reference to the accompanyingdrawings. Apparently, the described embodiments are merely some but notall of the embodiments of this application. All other embodimentsobtained by persons of ordinary skill in the art based on theembodiments of this application without creative efforts shall fallwithin the protection scope of this application.

In the following description, some terms in this application aredescribed, to help persons skilled in the art have a betterunderstanding.

(1) A terminal, also referred to as user equipment (UE), is a deviceproviding voice and/or data connectivity for a user, for example, ahandheld device or an in-vehicle device that have a wireless connectionfunction. Common terminals include, for example, a mobile phone, atablet computer, a laptop computer, a palmtop computer, a mobileInternet computer (MID), or a wearable device such as a smart watch, asmart band, or a pedometer.

(2) A base station, also referred to as a radio access network (RAN)device, is a device that connects a terminal to a wireless network,including but is not limited to an evolved node B (eNB), a radio networkcontroller (RNC), a node B (NB), a base station controller (BSC), a basetransceiver station (BTS), a home eNodeB (for example, Home evolvedNodeB or Home Node B, HNB), or a baseband unit (BBU). In addition, thebase station may include a Wi-Fi access point (AP) or the like.

(3) A unit (or entity) in this application means a function unit (orentity) or a logical unit (or entity). The unit may be in the form ofsoftware and its function is implemented by using a processor to executeprogram code, or may be in the form of hardware.

(4) “A plurality of” means two or more than two. The term “and/or”describes an association relationship for describing associated objectsand represents that three relationships may exist. For example, A and/orB may represent the following three cases: Only A exists, both A and Bexist, and only B exists. The character “/” generally indicates an “or”relationship between the associated objects. A scope described by using“above” or “below” includes a boundary point.

Referring to FIG. 1, FIG. 1 is a schematic diagram of a communicationscenario according to an embodiment of this application. As shown inFIG. 1, a terminal 110 accesses to a wireless network through a RANdevice 120, to obtain a service of an external network (for example, theInternet) through the wireless network, or to communicate with anotherterminal through the wireless network. In a downlink transmissiondirection, the RAN device 120 is used as a transmit end, and theterminal 110 may be used as a receive end. In an uplink transmissiondirection, the terminal 110 is used as a transmit end, and the RANdevice 120 is used as a receive end.

Communication between the terminal 110 and the RAN device 120 follows anair-interface protocol. Referring to FIG. 2, FIG. 2 is a schematicdiagram of a user plane protocol stack followed by communication betweena terminal and a RAN device according to an embodiment of thisapplication. As shown in FIG. 2, the protocol stack includes a PacketData Convergence Protocol (PDCP) layer, a Radio Link Control (RLC)layer, a Media Access Control (MAC) layer, and a physical (PHY) layer.The PDCP layer, the RLC layer, and the MAC layer form a layer-2 (L2)protocol stack.

Currently, main functions of the PDCP layer includeencryption/decryption, header compression/header decompression,integrity protection, and the like. Main functions of the RLC layerinclude segmentation, concatenation, reordering, automatic repeatrequest (ARQ), and the like. Main functions of the MAC layer includemultiplexing, scheduling, hybrid automatic repeat request (HARD), andthe like.

In a solution according to an embodiment of this application, functionsof the RLC layer are adjusted, and when encapsulating a data packet fromthe PDCP layer, the RLC layer performs segmentation only and does notperform concatenation. In this way, concatenation processing at thetransmit end can be reduced, and processing complexity and processinglatency can be reduced.

The following provides detailed description with reference to theaccompanying drawings. It may be understood that a transmit end in thisembodiment of this application may also be referred to as a data sendingapparatus, and a receive end may also be referred to as a data receivingapparatus.

Referring to FIG. 3, FIG. 3 is a schematic diagram of a data processingmethod according to an embodiment of this application. As shown in FIG.3, the method is used at a transmit end, that is, performed by thetransmit end, and the transmit end may also be referred to as a datasending apparatus. The method includes the following steps:

S310. Receive a data packet from a PDCP layer, and use the data packetas an RLC service data unit (SDU).

S320. Encapsulate the RLC SDU into at least one RLC PDU, where each theRLC PDU includes a header and a payload, and the payload is used tocarry data from a single RLC SDU.

In this embodiment and the following embodiments, that the payload ofthe RLC PDU is used to carry data from a single RLC SDU means that evenif the RLC PDU can accommodate more than one RLC SDU or more than onesegment of an RLC SDU, a payload of each the RLC PDU is used to carryonly data from a single RLC SDU. In other words, the transmit end doesnot perform concatenation processing at the RLC layer on the datapacket.

It can be learned that in a process where the transmit end encapsulates,at the RLC layer, the RLC SDU into the RLC PDU(s), the payload of eachassembled RLC PDU is used to carry data from a single RLC SDU. In otherwords, the payload of the RLC PDU does not include data of another RLCSDU. That is, the transmit end no longer performs concatenationprocessing at the RLC layer on RLC SDUs. In this way, concatenationprocessing at the transmit end can be reduced, and processing complexityand processing latency can be reduced.

In addition, the receive end may reorder, at the RLC layer, segments ofa single RLC SDU only, without a need to reorder RLC SDUs. Therefore,processing at the receive end can be simplified. This is described indetail in the following embodiments.

When concatenation processing is not performed on the RLC SDU, theheader of the RLC PDU may be further simplified to reduce headeroverheads of the RLC PDU. Certainly, an RLC PDU format in existingtechnology may still be used, except that larger header overheads areneeded as compared with a simplified RLC PDU format in this application.

Referring to FIG. 4, FIG. 4 is a schematic diagram of a format of an RLCPDU according to an embodiment of this application. As shown in FIG. 4,the RLC PDU includes a header and a payload, and the payload is used tocarry data from a single RLC SDU. The header is also referred to as apacket header, including one or more of the following fields: adata/control (D/C) field, a sequence number (SN) field, a segmentindicator (SI) field, and a segment offset (SO) field.

The D/C field is used to indicate whether a data packet or a controlpacket is transmitted or whether data information or control informationis transmitted in the RLC PDU where the D/C field is located. Forexample, when the D/C field is 0, a data packet is transmitted in theRLC PDU, and when the D/C field is 1, a control packet is transmitted inthe RLC PDU, or vice versa. That is, when the D/C field is 0, a controlpacket is transmitted in the RLC PDU, and when the D/C field is 1, adata packet is transmitted in the RLC PDU. This is not limited in thisembodiment.

The SN field is used to indicate an RLC SDU to which data transmitted inthe RLC PDU where the SN field is located belongs. In existingtechnology, each RLC PDU corresponds to one SN. In this embodiment, eachRLC SDU corresponds to one SN. If one RLC SDU is divided into aplurality of segments and encapsulated into a plurality of RLC PDUs, SNsin these RLC PDUs are the same. It can be learned that in thisembodiment, the SN field may be used to indicate a sequence numbercorresponding to the RLC SDU to which the data transmitted in the RLCPDU where the SN field is located belongs.

It can be learned that one RLC SDU corresponds to one SN, and when oneRLC SDU is encapsulated into a plurality of RLC PDUs for transmission,the plurality of RLC PDUs use a same SN. In this way, the PDCP layer andthe RLC layer may share one SN to reduce header overheads. In addition,this resolves a problem that an SN length needs to be extended inexisting technology because a plurality of SNs is needed when the RLCSDU is segmented into a plurality of RLC PDUs, and therefore can alsoreduce overheads.

A length of the SN field may be agreed, or may be configured by an upperlayer, for example, the radio resource control (RRC) layer. The lengthof the SN field is not limited in this embodiment and may be configuredor agreed based on a need, for example, may be five bits or ten bits.

Optionally, an SN in the SN field may be allocated by the RLC layer. Inthis case, the RLC PDU and the PDCP PDU include their respective SNs. Inother words, one RLC PDU includes two SNs. Optionally, an SN in the SNfield may be configured by the PDCP layer. In other words, an SNincluded in the RLC PDU is an SN allocated by the PDCP layer. In thiscase, one RLC PDU includes only one SN, and one RLC SDU is encapsulatedinto a plurality of RLC PDUs that have same SNs. In this way, the PDCPlayer and the RLC layer may share one SN to reduce header overheads. Inaddition, this resolves a problem that an SN length needs to be extendedin the existing technology because a plurality of SNs is needed when theRLC SDU is segmented into a plurality of RLC PDUs, and therefore canalso reduce overheads.

Optionally, at the transmit end, the SN field may be used to control aposition and/or a size of an RLC transmit window, and perform, based ona status report fed back by the receive end, an operation such as ARQretransmission. At the receive end, the SN field may be used to performoperations such as reordering, status report feedback, and RLC SDUreassembly.

The SI field is used to indicate what is encapsulated into an RLC PDUwhere the SI field is located is a complete RLC SDU or a segment of anRLC SDU, namely, whether the payload of the RLC PDU is a complete RLCSDU or a segment of an RLC SDU.

In an implementation, the SI field may include two bits. Differentvalues represent different meanings. The following provides anembodiment (embodiment 1).

-   -   00: indicates no segmentation. Herein, the segmentation means        segmentation performed on an RLC SDU. That is, what is        encapsulated into the RLC PDU is a complete RLC SDU.    -   01: indicates a first segment. That is, what is encapsulated        into the RLC PDU is a first segment of an RLC SDU.    -   10: indicates a middle segment. That is, what is encapsulated        into the RLC PDU is a middle segment of an RLC SDU. The middle        segment does not include a first byte of the RLC SDU, and does        not include a last byte of the RLC SDU. In other words, the        middle segment is neither a first segment of the RLC SDU nor a        last segment of the RLC SDU.    -   11: indicates a last segment. That is, what is encapsulated into        the RLC PDU is a last segment of an RLC SDU.

In another embodiment (embodiment 2), a correspondence between values ofthe SI and meanings indicated by the values may be optimized as follows:

-   -   00: indicates no segmentation. Herein, the segmentation means        segmentation performed on an RLC SDU. That is, what is        encapsulated into the RLC PDU is a complete RLC SDU.    -   01: reserved.    -   10: reserved.    -   11: indicates a last segment. That is, what is encapsulated into        the RLC PDU is a last segment of an RLC SDU.

The “reserved” herein means that a meaning of the value is temporarilynot defined.

In another implementation, the SI field may include one bit. Differentvalues represent different meanings. The following provides anembodiment (embodiment 3).

-   -   0: indicates a first segment or a middle segment. That is, what        is encapsulated into the RLC PDU is a first segment or a middle        segment of an RLC SDU. The middle segment does not include a        first byte of the RLC SDU, and does not include a last byte of        the RLC SDU. In other words, the middle segment is neither a        first segment of the RLC SDU nor a last segment of the RLC SDU.    -   1: indicates no segmentation or a last segment. Herein, the        segmentation means segmentation performed on an RLC SDU. That        is, what is encapsulated into the RLC PDU is a complete RLC SDU        or what is encapsulated into the RLC PDU is a last segment of an        RLC SDU.

It may be understood that a correspondence between each way of valueassignment and a meaning indicated by each value in the way of valueassignment is not intended to limit this application, and another way ofvalue assignment may be used in the correspondence. For example, morebits are used. For another example, in each way of value assignment, acorrespondence between a value and a meaning of the value may beexchanged.

The SO field is used to indicate a byte offset, of a first byte in apayload of the RLC PDU where the SO field is located, within an RLC SDUto which the payload belongs. When the RLC PDU includes a complete RLCSDU, the first byte in the payload of the RLC PDU is a first byte of theRLC SDU, and therefore, the byte offset indicated by the SO field is 0.When the RLC PDU includes a segment of an RLC SDU, the byte offsetindicated by the SO field is a byte offset, of a first byte in thesegment, within the RLC SDU. For example, a size of an RLC SDU is 400bytes. It is assumed that the RLC SDU is divided into two 200-bytesegments. In an RLC PDU where a first segment is located, a value of theSO field is 0, and in an RLC PDU where a second segment is located, avalue of the SO field is 201. When the value of the SO field is 0, theSO field may be spared. In other words, there is no SO field. In thiscase, it is considered that the RLC PDU includes the complete RLC SDU,or includes the first segment of the RLC SDU.

A length of the SO field is not limited in this application. The lengthof the SO field may be related to a size of the RLC SDU or a segment ofthe RLC SDU, or related to a size of the payload of the RLC PDU. Whenthe payload in the RLC PDU is greater, the SO field needs to be longer,but the length of the SO field is not directly proportional to thepayload in the RLC PDU. For example, when the SO field includes one bit,a payload size of a maximum RLC PDU that can be indicated is 2; or whenthe SO field includes two bits, a payload size of a maximum RLC PDU thatcan be indicated is 4, and so on. When a 200-byte RLC PDU payload needsto be indicated, the length of the SO field needs to be eight bits. Thelength of the SO field may be agreed, or may be configured by an upperlayer, for example, an RRC layer. Alternatively, a field, namely, alength indicator field of the SO field, may be added to the header ofthe RLC PDU, to indicate the length of the SO field. For example, a1-bit field may be used to indicate two SO lengths, and a 2-bit fieldmay be used to indicate four SO lengths.

The SI field may be combined with the SO field to indicate specificinformation of the RLC SDU or a segment of the RLC SDU that is includedin the RLC PDU, to facilitate reassembly of the RLC SDU at the receiveend.

In correspondence to embodiment 1 to embodiment 3, embodiments of acombination of the SI field and the SO field are as follows:

Embodiment 1

In correspondence to the foregoing embodiment 1, a way of valueassignment of the SI field and meanings of values of the SI field arethe same as those in the foregoing embodiment 1.

-   -   SI=00, and SO=0, or no SO field: indicates no segmentation.        Herein, the segmentation means segmentation performed on an RLC        SDU. That is, what is encapsulated into the RLC PDU is a        complete RLC SDU.    -   SI=01, and SO=0, or no SO field: indicates a first segment. That        is, what is encapsulated into the RLC PDU is a first segment of        an RLC SDU.    -   SI=10 and SO=M, where M>0: indicates a middle segment. That is,        what is encapsulated into the RLC PDU is a middle segment of an        RLC SDU. A meaning of the middle segment is the same as the        foregoing description, and details are not described herein        again.    -   SI=11 and SO=N, where N>0: indicates a last segment. That is,        what is encapsulated into the RLC PDU is a last segment of an        RLC SDU.

Embodiment 2

In correspondence to the foregoing embodiment 2, a way of valueassignment of the SI field and meanings of values of the SI field arethe same as those in the foregoing embodiment 2.

-   -   SI=00 and SO=0: indicates no segmentation. Herein, the        segmentation means segmentation performed on an RLC SDU. That        is, what is encapsulated into the RLC PDU is a complete RLC SDU.    -   SI=11, and SO=N, where N>0: indicates a last segment. That is,        the RLC PDU includes a last segment of an RLC SDU.    -   SI≠00 and SI≠11, for example, SI=01 or SI=10, and SO=M, where        M>0: indicates a middle segment. That is, what is encapsulated        into the RLC PDU is a middle segment of an RLC SDU. A meaning of        the middle segment is the same as the foregoing description, and        details are not described herein again.

Embodiment 3

In correspondence to the foregoing embodiment 3, a way of valueassignment of the SI field and meanings of values of the SI field arethe same as those in the foregoing embodiment 3.

-   -   SI=0 and SO=0: indicates a first segment. That is, what is        encapsulated into the RLC PDU is a first segment of an RLC SDU.    -   SI=0 and SO=M, where M>0: indicates a middle segment.    -   SI=1 and SO=0: indicates no segmentation. Herein, the        segmentation means segmentation performed on an RLC SDU. That        is, what is encapsulated into the RLC PDU is a complete RLC SDU.    -   SI=1, and SO=N, where N>0: indicates a last segment. That is,        what is encapsulated into the RLC PDU is a last segment of an        RLC SDU.

Optionally, the header of the RLC PDU may further include a pollingfield. The polling field is used to request the RLC layer at the receiveend to feed back an RLC status report. The polling field is the same asthat in the existing technology, and details are not described herein.

Optionally, the header of the RLC PDU may further include at least onereserved field for subsequent function extension.

In an implementation, the transmit end may assemble, at the RLC layer,the RLC PDU based on an indication from a lower layer, for example, aMAC layer. For example, when a size indicated by the MAC layer canaccommodate an RLC SDU plus a corresponding RLC header, the transmit endencapsulates, at the RLC layer, the whole RLC SDU into one RLC PDU. TheRLC SDU in the RLC PDU is not segmented, no data of another RLC SDU isconcatenated, and there is no padding greater than one byte. In otherwords, the padding is generated for byte alignment. For another example,when a size indicated by the MAC layer cannot accommodate an RLC SDUplus a corresponding RLC header, the transmit end divides the RLC SDUinto a plurality of segments and encapsulates each segment into one RLCPDU. Currently, the MAC layer is used for resource scheduling. A size ofa RLC PDU that should assembled by the RLC layer or a total size ofplurality of RLC PDUs that should be assembled by the RLC layer may belearned based on a resource scheduling situation of the MAC layer.

In another implementation, a size of the RLC PDU may be preset, so thatthe transmit end may assemble, at the RLC layer, the RLC PDU based onthe preset RLC PDU size. In this case, the RLC layer may assemble theRLC PDU in advance before the MAC layer finishes scheduling or beforereceiving a size indicated by the MAC layer, and may directly deliver acorresponding quantity of RLC PDUs to the MAC layer after receiving anindication from the MAC layer, so that a real-time processing time ofthe RLC layer is effectively reduced and a data transmission delay isreduced. The assembly process is similar to the process where the RLCPDU is assembled based on the indication from the MAC layer. Forexample, when the preset RLC PDU size can accommodate an RLC SDU plus acorresponding RLC header, the transmit end encapsulates, at the RLClayer, the whole RLC SDU into one RLC PDU. The RLC SDU in the RLC PDU isnot segmented, and no data of another RLC SDU is concatenated. To enablea size of the assembled RLC PDU to be the same as the preset size, inthis case, the transmit end may perform padding at the RLC layer.Alternatively, padding may not be performed, in other words, the presetRLC PDU size is a limit value and is merely used to limit a maximumvalue of the size of the assembled RLC PDU. For another example, whenthe preset RLC PDU size cannot accommodate an RLC SDU plus acorresponding RLC header, the transmit end divides the RLC SDU into aplurality of segments and encapsulates each segment into one RLC PDU.The transmit end may segment the RLC SDU based on the preset RLC PDUsize, so that all sizes of RLC PDUs formed by segments except a lastsegment meet the preset RLC PDU size; and for the last segment, when asize of the last segment is insufficient to form an RLC PDU of thepreset size, padding may be performed, or padding may not be performed,and this is not limited herein.

Referring to FIG. 5, FIG. 5 is a schematic diagram of another format ofan RLC PDU according to an embodiment of this application. A differencefrom the RLC PDU format shown in FIG. 4 is that this format furtherincludes a length indicator (LI) field, used to indicate a length of apayload in an RLC PDU where the LI field is located. That is, the LIfield is used to indicate a length of an SDU or an SDU segment in theRLC PDU where the LI field is located.

Optionally, the transmit end may send, at the RLC layer, the RLC PDUsone by one to the MAC layer. In this case, the MAC layer considers eachRLC PDU as one MAC SDU, and sets one subheader for each MAC SDU toindicate the MAC SDU. Alternatively, the transmit end may send, at theRLC layer, a plurality of RLC PDUs as one RLC data packet to the MAClayer, as shown in FIG. 6. The MAC layer uses the RLC data packet as oneMAC SDU. Therefore, only one subheader needs to be added to the MAC SDUto indicate the MAC SDU, and header overheads of the MAC layer arereduced. This is described in detail in the following data processingprocess at the MAC layer, and details are not described herein.

It can be learned that the transmit end sends an RLC data packet to theMAC layer, and the RLC data packet may include one RLC PDU, or mayinclude a plurality of RLC PDUs. In addition, data encapsulated in theRLC PDU included in one RLC data packet may be from one RLC SDU or maybe from a plurality of RLC SDUs.

To help persons skilled in the art have a better understanding, thefollowing provides description with reference to processing processes ateach layer. However, this is not intended to limit this application.Data processing units or entities at various layers in this applicationmay be located on different devices on a RAN side.

Referring to FIG. 7, FIG. 7 is a flowchart of a data processing methodaccording to an embodiment of this application. As shown in FIG. 7, themethod includes the following steps.

S710. Upper-layer data (a PDCP SDU) reaches a PDCP layer. At the PDCPlayer, a transmit end processes the data to form a PDCP PDU, and sendsthe PDCP PDU to an RLC layer.

The data processing performed at the PDCP layer by the transmit end mayinclude one or more operations such as header compression, encryption,and integrity protection. This is the same as that in the existingtechnology. Details are not described herein.

Optionally, the transmit end allocates one SN to the PDCP PDU orassociates one SN with the PDCP PDU at the PDCP layer. The SN may beencapsulated into the PDCP PDU to be sent to the RLC layer.Alternatively, the SN is not encapsulated into the PDCP PDU, but is sentwith the PDCP PDU to the RLC layer. Alternatively, the SN is notencapsulated into the PDCP PDU, but is separately sent to the RLC layer,and signaling is used to indicate a correspondence between the SN andthe PDCP PDU, that is, indicate a specific PDCP PDU to which the SN isallocated. To distinguish between the SN and an RLC-layer SN, this SN isreferred to as a PDCP SN. The PDCP SN may be the same as the RLC-layerSN or different from the RLC-layer SN.

Optionally, the transmit end may maintain, at the PDCP layer, a PDCPtransmit window, to control data packet sending at the PDCP layer. Thiscan effectively reduce a problem that PDCP SNs are repeated when anamount of data sent by the transmit end exceeds a range of data that canbe indicated by the PDCP SNs, thereby resolving a problem that a receiveend cannot correctly distinguish and process a plurality of data packetsthat have same SNs and that are received at the PDCP layer. After thetransmit end consecutively sends, at the PDCP layer, a maximum quantityof PDCP PDUs that can be accommodated by the PDCP transmit window, if nostatus report about successful sending or successful receiving fed backby a lower layer (for example, the RLC layer) or the receive end isreceived, the transmit end no longer sends any PDCP PDU. When thetransmit end uses an unacknowledged mode (UM) at the RLC layer, theremay be no PDCP transmit window. The status report about successfulsending herein is a status report fed back at the RLC layer by thetransmit end, indicating that all or some PDCP PDUs are successfullysent, and the status report about successful receiving is a statusreport fed back by the receive end, indicating that all or some PDCPPDUs are successfully received.

A size of the PDCP transmit window may be preconfigured. Alternatively,a size of the PDCP transmit window may be determined based on an SNlength. When the size of the PDCP transmit window is determined based onthe SN length, the following formula may be used for the determining:W=(L+1)/2, where W denotes the size of the PDCP transmit window, and Ldenotes a value of a maximum SN that can be indicated by the SN length.For example, when the SN length is 10 bits, the maximum SN that can beindicated is 1023. Therefore, the size of the PDCP transmit window is(1023+1)/2=512.

S720. The transmit end receives, at the RLC layer, the PDCP PDU from thePDCP layer, uses the PDCP PDU as an RLC SDU, processes, at the RLClayer, the RLC SDU to form an RLC PDU, and sends the RLC PDU to a MAClayer.

In the existing technology, the transmit end may perform, at the RLClayer, two kinds of operations on the RLC SDU: concatenation andsegmentation. In this embodiment, only segmentation processing isretained at the RLC layer, and concatenation processing is no longerperformed on RLC SDUs. In this way, processing complexity and processinglatency may be reduced. In addition, because the complexity is reduced,a requirement for an RLC PDU header is also lowered, and overheads ofthe RLC PDU header may be reduced.

For a process where the RLC layer processes a data packet from the PDCPlayer, refer to the foregoing embodiments, and details are not describedherein again.

In addition, an SN in the RLC PDU may be the SN delivered by the PDCPlayer in step S710. In other words, the SN in the RLC PDU is the same asthe PDCP SN. In this way, the PDCP layer and the RLC layer may share oneSN to reduce header overheads. In addition, this resolves a problem thatan SN length needs to be extended in the existing technology because aplurality of SNs is needed when the RLC SDU is segmented into aplurality of RLC PDUs, and therefore can also reduce overheads.

S730. The transmit end receives, at the MAC layer, an RLC data packetfrom the RLC layer, uses the RLC data packet as a MAC SDU, processes, atthe MAC layer, the MAC SDU to form a MAC PDU, which is also referred toas a transport block (TB), and sends the MAC PDU to a physical layer.

It should be noted that the transmit end may receive, at the MAC layer,RLC data packets from one or more RLC layers, and each RLC layercorresponds to one radio bearer.

The MAC PDU includes a MAC header and a MAC payload, the MAC headerincludes a plurality of subheaders, and each subheader is used toindicate one MAC control element (CE) or one MAC SDU.

Referring to FIG. 8, FIG. 8 is a schematic structural diagram of anexisting MAC PDU. As shown in FIG. 8, generally, the MAC PDU includes aMAC header and a MAC payload. The MAC payload includes a MAC SDU and/ora MAC CE, and optionally, may further include a padding. For each MACSDU, there is an associated subheader in a MAC header. A common MAC PDUsubheader includes six fields (R/R/E/LCID/F/L) and may have two forms:one with a 7-bit L field and the other with a 15-bit L field. For a lastsubheader, a subheader corresponding to a MAC control element of a fixedlength, and a subheader corresponding to the padding, four fields(R/R/E/LCID) are included. R is a reserved bit and is set to “0”. E isused to indicate whether the MAC header has a plurality of fields. Forexample, when E=1, it means that what follows next is another group of“R/R/E/LCID” fields, and when E=0, it means that what follows next isthe MAC payload. The logical channel identifier (LCD) is used toidentify a logical channel from which a corresponding RLC PDUoriginates. F is used to indicate a length of the L field. L is used toindicate a length of the MAC SDU or a length of a control message.

In this embodiment of this application, a MAC PDU format the same asthat in the existing technology may be used, and only content of the MACSDU, namely, the RLC data packet, may be different from that in theexisting technology. The RLC data packet may include a plurality of RLCPDUs in the foregoing format.

Optionally, in this embodiment of this application, a MAC PDU formatdifferent from that in the existing technology may be used, and a maindifference is that a second extension field is added to the MAC header.The second extension field may be indicated as an H field or an E2 field(in this case, an original extension field may be indicated as an E1field). The H field is used to indicate whether there is still an RLCdata packet on a logical channel indicated by an LCID in a MAC subheaderwhere the H field is located. For example, when the H field is 0, itrepresents that there is no RLC data packet on the logical channel, andwhen the H field is 1, it represents that there is an RLC data packet onthe logical channel, or vice versa. That is, when the H field is 0, itrepresents that there is an RLC data packet on the logical channel, andwhen the H field is 1, it represents that there is no RLC data packet onthe logical channel. In this way, only one LCID is needed to indicatedata of a single logical channel. Therefore, header overheads areeffectively reduced.

Referring to FIG. 9, FIG. 9 is a schematic structural diagram of a MACPDU according to an embodiment of this application. As shown in FIG. 9,the MAC PDU includes a MAC header and a MAC payload, the MAC headerincludes at least one subheader, and each subheader corresponds to onelogical channel. The logical channel is indicated by an LCID field. Inaddition, a payload associated with each subheader may include one ormore MAC SDUs, where some or all the MAC SDUs may be MAC CEs. Herein,for simplicity and convenience, only the MAC SDU is shown. Eachsubheader includes a first extension field and a second extension field,the first extension field is used to indicate whether the MAC PDUfurther includes another subheader or further includes data of anotherlogical channel, and the second extension field is used to indicatewhether the MAC PDU further includes other data of a logical channelcorresponding to a subheader where the second extension field islocated. In addition, the MAC subheader may further include an L fieldand an F field, and functions of the L field and the F field are similarto those in the existing technology.

As shown in FIG. 9, a subheader of the MAC PDU includes the followingfields:

LCID field: used to indicate an RLC layer or a logical channel fromwhich a payload associated with the subheader comes. It may beunderstood that payloads associated with the subheader, such as a MACSDU 1 and a MAC SDU 2, come from a single RLC layer or a single logicalchannel. Because a MAC layer may generate its own data, for example, aMAC CE, the payload is also identified by using a corresponding LCD.Herein, only the MAC SDU is shown. A case about the MAC CE is similar.

E field: a first extension field, used to indicate whether the MAC PDUfurther includes another subheader, namely, whether the MAC PDU furtherincludes data of another logical channel. For example, when E=0, itindicates that the MAC PDU does not have another subheader or data ofanother logical channel, and when E=1, it indicates that the MAC PDUincludes another subheader or data of another logical channel, or viceversa.

R field: a reserved field.

H field: a second extension field, used to indicate whether the MAC PDUfurther includes other data of a logical channel corresponding to asubheader where the H field is located, That is, used to indicatewhether there are other H/F/L fields. For example, when H=0, itrepresents that there are no other H/F/L fields, and when H=1, itrepresents that there are other H/F/L fields.

F field: used to indicate a length of the L field.

L field: used to indicate a length of the MAC SDU or a length of the MACCE.

Optionally, the subheader of the MAC PDU includes one group of LCID/E/Rfields, and one or more groups of H/F/L fields.

It should be noted that in addition to the format shown in FIG. 9,alternatively, subheaders may be centrally placed at the beginning ofthe MAC PDU, payloads associated with the subheader are placed at thelater part of the MAC PDU based on a sequence of the correspondingsubheaders, and there may be a padding field at the end. Alternatively,subheaders corresponding to a single LCID and payloads of the logicalchannel identified by the LCID may be centrally placed, with subheaderinformation placed at the beginning, and the payloads placed later. Forexample, as shown in FIG. 9, two parts of a subheader 1 are centrallyplaced at the beginning, and MAC SDU 1 and MAC SDU 2 are centrallyplaced later.

According to a manner where subheaders are separated according to LCIDs,each time a receive end decodes a subheader at the MAC layer, acorresponding payload may be decoded, and a time from reception toprocessing is reduced. A manner of centrally placing the subheaders maycomply with an existing standard, with relatively little modification.

S740. The transmit end sends data to a receive end through the physicallayer.

S750. The receive end restores, at an MAC layer, a received MAC PDU toan MAC SDU, and sends the MAC SDU to an RLC layer.

Optionally, when both the receive end and the transmit end use anexisting MAC PDU format, the receive end reassembles the MAC SDU basedon the existing MAC PDU format. When both the receive end and thetransmit end use the improved MAC PDU format in step S730, the receiveend reassembles the MAC SDU based on the improved MAC PDU format.

After the MAC SDU is reassembled at the MAC layer, the receive enddelivers, based on an LCD of a subheader corresponding to the MAC SDU,the MAC SDU to a corresponding RLC layer for processing.

S760. The receive end receives, at the RLC layer, the MAC SDU from theMAC layer, uses the MAC SDU as an RLC data packet, restores the receivedRLC data packet to an RLC SDU, and delivers the RLC SDU to a PDCP layer.

Similar to the foregoing description, the RLC data packet may includeone RLC PDU or may include a plurality of RLC PDUs.

When the RLC PDU includes a complete RLC SDU, the transmit end delivers,at the RLC layer, the RLC SDU to the PDCP layer for processing. When theRLC PDU includes a segment of an RLC SDU, and all segments of the RLCSDU are successfully received at the RLC layer, the transmit endrestores all the segments to the RLC SDU and delivers the RLC SDU to thePDCP layer for processing.

A format of the RLC PDU is the same as that in the foregoingdescription, and details are not described herein again.

Optionally, when the RLC SDU sent to the PDCP layer does not include aPDCP sequence number, the receive end sends an SN in an SN field in theRLC PDU to the PDCP layer. In other words, the receive end notifies thePDCP layer of an SN corresponding to the RLC SDU. The PDCP sequencenumber is a sequence number allocated to the PDCP PDU when the transmitend assembles the PDCP PDU. In this way, when the RLC SDU does notinclude a PDCP sequence number, the PDCP layer may perform, based on theSN delivered by the RLC layer, related processing, for example, one ormore of operations such as reordering, a security-related operation, andheader decompression.

Optionally, for an RLC unacknowledged mode (UM), the receive endmaintains, at the RLC layer, a reordering window. A main function of thereordering window is that when an RLC PDU where a segment not restoredto an RLC SDU is located falls out of the reordering window, the receiveend discards, at the RLC layer, all received RLC PDUs corresponding tothe RLC SDU. It may be understood that herein the falling out of thereordering window means falling out of a lower edge of the reorderingwindow. Further, optionally, the receive end may notify the PDCP layerof a sequence number of the discarded RLC SDU.

When the receive end receives an updated RLC PDU (a corresponding SNexceeds an upper edge of the current reordering window), the receive endslides the reordering window to the SN corresponding to the RLC PDU orto a sequence number that is obtained by adding 1 to the SNcorresponding to the RLC PDU. It may be understood that when an SN of areceived RLC PDU falls within the reordering window, the receive endtries, at the RLC layer, to restore the RLC PDU to an RLC SDU anddelivers the RLC SDU to the PDCP layer. When an SN of a received RLC PDUfalls out of the reordering window, the receive end directly discards,at the RLC layer, the RLC PDU.

Optionally, when SNs of received RLC PDUs are discontinuous, the receiveend starts an associated timer at a first discontinuous position. Beforethe associated timer expires, if RLC PDUs that include missing SNs arereceived, the receive end stops the associated timer. If the timerexpires, and RLC PDUs that include missing SNs are not received, thereceive end moves a lower edge of the reordering window to a position ofan SN corresponding to a first RLC SDU that is not delivered to an upperlayer and corresponding to the first discontinuous position, anddiscards an RLC PDU that is not delivered to the PDCP layer and whose SNis located before the SN. Further, optionally, the receive end maynotify the PDCP layer of an SN of an RLC SDU corresponding to thediscarded RLC PDU. For example, if SNs received by the receive end are1, 2, 5, 6, 7, and 10 respectively, the first discontinuous position isa position of 5 or a position immediately followed by 5. In this case,an SN corresponding to the first discontinuous position may be marked as5 or 4. The associated timer is started at the position of 5 or 4. Ifthe associated timer for the position of 4 or 5 expires, the receive endmoves the lower edge of the reordering window to a position whosecorresponding SN is 8, and discards an RLC PDU that is not delivered tothe PDCP layer and whose SN is located before 8. In this case, if SNs ofreceived RLC PDUs are 1, 2, 5, 6, 7, and 10, the associated timer isstarted at the position of 9 or 10 again. In addition, a length of theassociated timer may be configured by an upper layer or may be agreed,and this is not limited in this application.

Optionally, for an RLC acknowledged mode (AM), the receive endmaintains, at the RLC layer, a reordering window. A main function of thereordering window is to execute an ARQ. A lower edge of the reorderingwindow is a smallest SN in SNs of all RLC SDUs that are not delivered tothe PDCP layer. It may be understood that when an SN of a received RLCPDU falls within the reordering window, the receive end tries, at theRLC layer, to restore the RLC PDU to an RLC SDU and delivers the RLC SDUto the PDCP layer. When an SN of a received RLC PDU falls out of thereordering window, the receive end directly discards, at the RLC layer,the RLC PDU.

Further, optionally, when SNs of received RLC PDUs are discontinuous, anassociated timer is started at a first discontinuous position (at theposition of 4 or 5 if received SNs are 1, 2, 5, 6, 7, and 10). Beforethe associated timer expires, if missing RLC PDUs are received, theassociated timer stops. If the associated timer expires, an RLC statusreport is triggered.

When an RLC receive end feeds back the RLC status report, an assemblyformat of the RLC status report is as follows:

-   -   D/C field: Same as that in a data packet format. Details are not        described herein.    -   ACK_SN: An SN reflected in the RLC status report and immediately        following an SN of an RLC PDU that is received at the RLC layer        by the receive end.    -   NACK_SN: An SN that is reflected in the RLC status report for an        RLC PDU that fails to be received and that is before an SN of an        RLC PDU received at the RLC layer by the receive end. In other        words, at the RLC PDU transmit end, the RLC PDU indicated by        NACK_SN is sent at the transmit end earlier than the RLC PDU        indicated by ACK_SN.    -   SO_Start: When the receive end receives only a part (one or more        segments) of one RLC SDU, SO_Start indicates a start byte of the        received part.    -   SO_End: When the receive end receives only a part (one or more        segments) of one RLC SDU, SO_End indicates an end byte of the        received part.

Optionally, when a part of a single RLC SDU relates to two or morediscontinuous segments, the part may be indicated in the followingmanner:

A combination of NACK_SN, SO_Start, and SO_End is used. Each missingsegment is indicated by a combination of NACK_SN, SO_Start, and SO_End.An advantage is that the manner is simple; and a disadvantage is thatthere are two SNs for a single RLC SDU, and consequently overheads arerelatively large.

Alternatively, one NACK_SN and a plurality of combinations of SO_Startand SO_End are used. An advantage is that overheads are relativelysmall. A disadvantage is that a packet format is relatively complex, andan indicator field is needed to indicate a quantity of combinations ofSO_Start and SO_End in an RLC PDU corresponding to a NACK_SN, or toindicate whether there is another combination of SO_Start and SO_Endfollowing a combination of SO_Start and SO_End in an RLC PDUcorresponding to a NACK_SN.

After receiving feedback from the RLC layer at the receive end, when theRLC layer at the transmit end retransmits a RLC PDU, if the complete RLCPDU cannot be sent by using a physical-layer resource, the transmit endmay further segment the RLC PDU. A format of an RLC PDU after thesegmentation is the same as the foregoing format of the RLC PDU, exceptthat content of fields such as the SI field and the SO field changes.During retransmission, an RLC SDU or an RLC SDU segment that is includedin a corresponding initially transmitted or previous retransmitted RLCPDU may be further divided into RLC SDU segments or smaller RLC SDUsegments, or an RLC SDU segment included in a corresponding initiallytransmitted or previous retransmitted RLC PDU is further divided intosmaller RLC SDU segments, or two or more continuous segments that belongto one RLC SDU are combined into one SDU segment or a complete SDU andencapsulated into one RLC PDU. In a word, it suffices if payloads of theRLC PDU come from one RLC SDU.

It may be learned that the receive end does not reorder, at the RLClayer, RLC PDUs, but directly delivers an RLC SDU to an upper layerprovided that the RLC PDUs can be restored to the RLC SDU. Because thetransmit end does not perform concatenation, processing at the receiveend becomes quite simple and highly efficient, and processing latency isreduced. In addition, the receive end may maintain, at the RLC layer, areordering window and/or an associated timer to determine whether arelated RLC PDU needs to be discarded.

S770. The receive end receives, at the PDCP layer, the RLC SDU from theRLC layer, uses the RLC SDU as a PDCP PDU, restores the PDCP PDU to thePDCP SDU, and delivers the PDCP SDU to an upper layer for processing.

This process is the same as that in the existing technology, and detailsare not described herein.

Optionally, the receive end may maintain, at the PDCP layer, areordering window that is used for in-order delivery at the PDCP layer.For example, when an SN of a received PDCP PDU falls out of thereordering window, the receive end discards, at the PDCP layer, the PDCPPDU, and when an SN of a received PDCP PDU falls within the reorderingwindow, the receive end tries, at the PDCP layer, to restore the PDCPPDU to a PDCP SDU and delivers the PDCP SDU to the upper layer. It maybe understood that herein the falling out of the reordering window meansfalling out of a lower edge of the reordering window.

Further, optionally, when SNs of received PDCP PDUs are discontinuous,the receive end starts an associated timer at a first discontinuousposition (at 4 or 5 if the received SNs are 1, 2, 5, 6, 7, and 10). Inaddition, before the associated timer expires, if missing PDCP PDUs arereceived, the receive end stops the associated timer, and if the timerexpires, the receive end moves a lower edge of the reordering window toa position of an SN corresponding to a first PDCP SDU that is notdelivered to the upper layer and corresponding to the firstdiscontinuous position, for example, moves the lower edge to 8. If theassociated timer for 4 or 5 expires, the SNs of the received PDCP PDUsare 1, 2, 5, 6, 7, and 10. In this case, the associated timer is startedat 9 or 10 again. A length of the associated timer is configured by theupper layer or fixed by the protocol, and this is not limited in thisapplication.

After the PDCP layer receives information notified by the RLC layer thata data packet corresponding to an SN is no longer delivered, the PDCPlayer no longer expects to receive the data packet. Therefore, apossible operation is to deliver continuous data packets following theSN to the upper layer. If an associated SN of an ongoing associatedtimer is smaller than a maximum SN of a data packet that has beendelivered to the upper layer, the receive end stops the associatedtimer, and moves the associated timer to a position of an SN after themaximum SN and corresponding to a first PDCP SDU not delivered to theupper layer.

It may be learned that the receive end does not reorder, at the RLClayer, RLC PDUs, but directly delivers an RLC SDU to an upper layerprovided that the RLC PDUs can be restored to the RLC SDU. The PDCPlayer may perform processing, for example, decryption and headerdecompression, on a PDU that is first received. Compared with theexisting technology, it is not necessary to wait for the RLC layer toperform reordering before delivering the RLC SDU for processing, andprocessing time is reduced.

It may be understood that an embodiment of this application may includeone or more of the foregoing steps, for example, include one or more ofthe following steps: the step performed at the PDCP layer by thetransmit end, the step performed at the RLC layer by the transmit end,the step performed at the MAC layer by the transmit end, the stepperformed at the MAC layer by the receive end, the step performed at theRLC layer by the receive end, the step performed at the PDCP layer bythe receive end.

The methods disclosed in the foregoing embodiments may be performed by anetwork element on which the transmit end is located. For example, whenthe transmit end is located on a terminal, the foregoing methods may beperformed by the terminal, and when the transmit end is located on a RANside, the foregoing methods may be performed by a RAN device. Inaddition, the terminal or the RAN device includes a data processingapparatus, and the data processing apparatus includes units forperforming the steps in any one of the foregoing methods.

Referring to FIG. 10, FIG. 10 is a schematic structural diagram of adata processing apparatus according to an embodiment of thisapplication. The apparatus is located at a transmit end, and isconfigured to perform some or all operations performed by the transmitend in the foregoing solutions. As shown in FIG. 10, the data processingapparatus 100 includes a receiving unit 101 and a processing unit 102.The receiving unit 101 is configured to receive a data packet from aPDCP layer, where the data packet is used as an RLC SDU. The processingunit 102 is configured to encapsulate the RLC SDU into at least one RLCPDU, where each the RLC PDU encapsulated at an RLC layer by theprocessing unit 102 includes a header and a payload, and the payload isused to carry data from a single RLC SDU.

Description about the header of the RLC PDU is the same as that in theforegoing embodiments, and details are not described herein again.

In addition, the processing unit 102 may encapsulate the RLC SDU intothe at least one RLC PDU based on an indication from a MAC layer, orencapsulate the RLC SDU into the at least one RLC PDU based on a presetRLC PDU size. For details, refer to the description in the foregoingembodiments.

Still referring to FIG. 10, optionally, the data processing apparatus100 may further include a sending unit 103, configured to send an RLCdata packet to the MAC layer. The RLC data packet includes one or moreRLC PDUs. Optionally, the data processing apparatus 100 may furtherinclude a processing unit 104, configured to use the RLC data packet asa MAC SDU and encapsulate the MAC SDU into a MAC PDU. The MAC PDUincludes a MAC header and a MAC payload, the MAC header includes atleast one subheader, each subheader corresponds to one logical channel,the subheader includes a first extension field and a second extensionfield, the first extension field is used to indicate whether the MAC PDUfurther includes another subheader or further includes data of anotherlogical channel, and the second extension field is used to indicatewhether the MAC PDU further includes other data of a logical channelcorresponding to a subheader where the second extension field islocated.

It should be noted that when the MAC layer and the RLC layer arearranged on different physical entities, the data processing apparatus100 may not include the processing unit 104, and the RLC data packet issent to the MAC layer located on another physical entity, forprocessing.

Referring to FIG. 11, FIG. 11 is a schematic structural diagram of adata processing apparatus according to an embodiment of thisapplication. The apparatus is located at a receive end, and isconfigured to perform some or all operations performed by the receiveend in the foregoing solutions. As shown in FIG. 11, the data processingapparatus 1100 includes a receiving unit 1101, a processing unit 1102,and a sending unit 1103. The receiving unit 1101 is configured toreceive, at an RLC layer, a data packet from a MAC layer, where the datapacket includes an RLC PDU, the RLC PDU includes a header and a payload,and the payload is used to carry data from a single RLC SDU. Theprocessing unit 1102 is configured to: when determining, based on theheader of the RLC PDU, that the payload of the RLC PDU is a complete RLCSDU, obtain the RLC SDU, and the sending unit 1103 is configured to sendthe RLC SDU to a PDCP layer; or the processing unit 1102 is configuredto: when determining, based on the header of the RLC PDU, that thepayload of the RLC PDU is a segment of an RLC SDU, obtain all segmentsof the RLC SDU and restore all the segments to the RLC SDU, and thesending unit 1103 is configured to send the RLC SDU to a PDCP layer.

Description about the header of the RLC PDU is the same as that in theforegoing embodiments, and details are not described herein again.

Optionally, when the RLC SDU sent to the PDCP layer does not include aPDCP SN, the sending unit 1103 is further configured to send an SN inthe RLC PDU to the PDCP layer.

Optionally, the data processing apparatus 1100 further includes aprocessing unit 1104, configured to: before the receiving unit 1101receives the data packet from the MAC layer, obtain, at the MAC layer, aMAC SDU based on a format of a MAC PDU, and use the MAC SDU as the datapacket sent to the RLC layer. The format of the MAC PDU is the same asthat in the foregoing embodiments, and details are not described hereinagain.

It should be noted that when the MAC layer and the RLC layer arearranged on different physical entities, the data processing apparatus1100 may not include the processing unit 1104, and the RLC data packetis sent to the MAC layer located on another physical entity, forprocessing.

It should be understood that division of the units in the foregoing dataprocessing apparatus 100 is merely logical function division. In actualimplementation, all or some of the units may be integrated into onephysical entity, or the units may be physically separated. In addition,these units may all be implemented in the form of software invoked byusing a processing element, or may all be implemented in the form ofhardware, or some units may be implemented in the form of softwareinvoked by using a processing element and some units be implemented inthe form of hardware. For example, the processing unit may be anindependently disposed processing element, or may be integrated into achip of a RAN device or a terminal, for implementation. In addition, theprocessing unit may be stored, in the form of a program, in a memory ofa RAN device or a terminal, and be invoked by a processing element inthe RAN device or the terminal, to perform the functions of theforegoing units. Implementation of other units is similar to this. Inaddition, all or some of these units may be integrated or these unitsmay be implemented separately. The processing element herein may be anintegrated circuit and have a signal processing capability. In animplementation process, the steps of the foregoing methods or theforegoing units may be performed by an integrated logical circuit in theform of hardware in the processing unit or by an instruction in the formof software in the processing unit.

For example, the foregoing units may be configured as one or moreintegrated circuits that perform the foregoing methods, for example, oneor more application-specific integrated circuits (ASIC), one or moremicroprocessors (digital signal processor, DSP), or one or more fieldprogrammable gate arrays (FPGA). For another example, when one of theforegoing units is implemented in the form of a program invoked by usinga processing element, the processing element may be a general purposeprocessor, for example, a central processing unit (CPU), or anotherprocessor that can invoke the program. For another example, these unitsmay be integrated together and implemented in the form of aSystem-On-a-Chip (SOC).

Implementation of the units of the data processing apparatus 1100 issimilar to this, and details are not described herein.

In addition, alternatively, data processing performed at the PDCP layerby the transmit end may be implemented by a data processing apparatus,and the data processing apparatus includes units that perform all orsome of the steps performed at the PDCP layer by the transmit end in theforegoing embodiments. Likewise, alternatively, data processingperformed at the PDCP layer by the receive end may be implemented by adata processing apparatus, and the data processing apparatus includesunits that perform all or some of the steps performed at the PDCP layerby the receive end in the foregoing embodiments.

Likewise, alternatively, data processing performed at the MAC layer bythe transmit end may be implemented by a data processing apparatus, andthe data processing apparatus includes units that perform all or some ofthe steps performed at the MAC layer by the transmit end in theforegoing embodiments. Likewise, alternatively, data processingperformed at the MAC layer by the receive end may be implemented by adata processing apparatus, and the data processing apparatus includesunits that perform all or some of the steps performed at the MAC layerby the receive end in the foregoing embodiments.

Referring to FIG. 12, FIG. 12 is a schematic structural diagram of adata processing apparatus according to an embodiment of thisapplication. As shown in FIG. 12, the data processing apparatus 1200includes a processor 1201 and a memory 1202. The processor 1201 invokesa program stored in the memory 1202, to perform all or some of the stepsperformed by the transmit end or the receive end in the foregoingembodiments, for example, the operations performed at any one of thePDCP layer, the RLC layer, and the MAC layer by the transmit end in theforegoing embodiments, or the operations performed at any one of thePDCP layer, the RLC layer, and the MAC layer by the receive end in theforegoing embodiments.

Referring to FIG. 13, FIG. 13 is a schematic structural diagram of aterminal according to an embodiment of this application. As shown inFIG. 13, the terminal includes a processor 1301, a memory 1302, and atransceiver apparatus 1303. The transceiver apparatus 1303 may beconnected to an antenna. In a downlink direction, the transceiverapparatus 1303 receives, by using the antenna, information sent by a RANdevice, and sends the information to the processor 1301 for processing.In an uplink direction, the processor 1301 processes data of theterminal, and sends the data to the RAN device by using the transceiverapparatus 1303.

When the terminal is a transmit end, the terminal includes any one ofthe foregoing data processing apparatuses configured to perform theoperations of the transmit end, for example, the data processingapparatus shown in FIG. 10 or FIG. 12. The units in FIG. 10 may beimplemented by using the processor 1301 to invoke program code in thememory 1302, or may be integrated into a chip in the terminal.

When the terminal is a receive end, the terminal includes any one of theforegoing data processing apparatuses configured to perform theoperations of the receive end, for example, the data processingapparatus shown in FIG. 11 or FIG. 12. The units in FIG. 11 may beimplemented by using the processor 1301 to invoke program code in thememory 1302, or may be integrated into a chip in the terminal.

Referring to FIG. 14, FIG. 14 is a schematic structural diagram of a RANdevice according to an embodiment of this application. As shown in FIG.14, the RAN device includes an antenna 1410, a radio frequency apparatus1420, and a baseband apparatus 1430. The antenna 1410 is connected tothe radio frequency apparatus 1420. In an uplink direction, the radiofrequency apparatus 1420 receives, by using the antenna 1410,information sent by a terminal, and sends, to the baseband apparatus1430 for processing, the information sent by the terminal. In a downlinkdirection, the baseband apparatus 1430 processes the information of theterminal and sends processed information to the radio frequencyapparatus 1420, and the radio frequency apparatus 1420 sends processedinformation to the terminal by using the antenna 1410 after processingthe information of the terminal.

When the RAN device is a transmit end, the RAN device includes any oneof the foregoing data processing apparatuses configured to perform theoperations of the transmit end, and the data processing apparatus islocated in the baseband apparatus 1430. For example, the data processingapparatus shown in FIG. 10 or FIG. 12 may be located in the basebandapparatus 1430.

In an implementation, the units shown in FIG. 10 are implemented byusing a processing element to invoke a program. For example, thebaseband apparatus 1430 includes a processing element 1431 and a storageelement 1432, and the processing element 1431 invokes a program storedin the storage element 1432, to implement the functions of the units. Inaddition, the baseband apparatus 1430 may further include an interface1433, configured to exchange information with the radio frequencyapparatus 1420. The interface is, for example, a common public radiointerface (CPRI).

In another implementation, these units may be configured as one or moreprocessing elements, and these processing elements are arranged on thebaseband apparatus 1430. The processing element herein may be anintegrated circuit, for example, one or more ASICs, one or more DSPs, orone or more FPGAs. These integrated circuits may be integrated to form achip.

For example, the foregoing units may be integrated together andimplemented in the form of a System-On-a-Chip (SOC). For example, thebaseband apparatus 1430 includes an SOC chip, configured to implementthe foregoing units.

Same as that in the foregoing description, the processing element hereinmay be a general purpose processor, for example, a central processingunit (CPU), or may be configured as one or more integrated circuits thatperform the foregoing methods, for example, one or more ASICs, one ormore DSPs, or one or more FPGAs.

The storage element may be a memory, or may be a general name for aplurality of storage elements.

Persons of ordinary skill in the art may understand that all or some ofthe steps of the method embodiments may be implemented by a programinstructing relevant hardware. The program may be stored in a computerreadable storage medium. When the program runs, the steps of the methodembodiments are performed. The foregoing storage medium includes: anymedium that can store program code, such as a ROM, a RAM, a magneticdisk, or an optical disc.

In addition, in the existing technology, a measurement gap is used totemporarily interrupt communication of a current serving cell when theterminal performs inter-frequency measurement. The measurement gap isconfigured at a granularity of a terminal. After the configuration, themeasurement is performed at a granularity of a terminal. That is, whenan RAN device configures, for a terminal, a measurement gap parameter,such as a measurement gap period and a measurement gap offset, theterminal does not receive, during a corresponding measurement gapperiod, information in the current serving cell or at a current servingfrequency. However, this affects normal communication between theterminal and the current serving cell. Therefore, an embodiment of thisapplication provides a measurement gap at a granularity of a carrier.However, currently, there is no method for configuring the measurementgap at the granularity of a carrier.

An embodiment of this application provides a method for configuring ameasurement gap parameter. The method is used on a RAN device. In otherwords, the method is performed by the RAN device. Referring to FIG. 15,the method includes the following steps.

S1510. The RAN device determines a measurement gap configurationparameter.

The measurement gap configuration parameter includes at least thefollowing:

information about one or more measurement frequencies or measurementbands;

information about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information can be normally received and sent when theterminal measures one or more measurement frequencies or measurementbands, namely, information receiving and sending cannot be performed inother serving cells (or serving frequencies or serving bands); orinformation about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information cannot be normally received and sent when theterminal measures one or more measurement frequencies or measurementbands; and

measurement gap pattern information, for example, a measurement gapperiod and a measurement gap offset, where optionally, the measurementgap pattern information further includes measurement gap lengthinformation (for example, 6 ms, 4 ms, or 3 ms).

Optionally, the foregoing measurement gap parameter further includesinformation about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information can be received and sent in part of time whenthe terminal measures one or more measurement frequencies or measurementbands. That information can be received and sent in part of time meansthat: the terminal can receive and send information in the one or morecurrent serving cells (or at the one or more serving frequencies, or inthe one or more serving bands) within a measurement period, except for atime period needed for the terminal to adjust a radio frequency from afrequency corresponding to the information about the one or more currentserving cells (or the information about the one or more servingfrequencies, or the information about the one or more serving bands) toa frequency at which the one or more measurement frequencies ormeasurement bands can be measured, and except for a time period neededfor the terminal to adjust a radio frequency from a frequency at whichthe one or more measurement frequencies or measurement bands can bemeasured to a frequency corresponding to the information about the oneor more current serving cells (or the information about the one or moreserving frequencies, or the information about the one or more servingbands). For example, according to measurement gap parameter information,the terminal needs to measure a frequency f1 during moments 0 to 5, andthe terminal currently works at a frequency of f2. It is assumed thatthe terminal needs to take 1 ms to adjust a radio frequency from f2 to afrequency at which f1 can be measured, and the terminal needs to take 1ms to adjust the radio frequency from the frequency at which f1 can bemeasured back to f2. Therefore, a time during which the terminal canreceive and send information at f1 are moments 1 to 4. Alternatively,the foregoing measurement gap parameter includes information about oneor more serving cells (or information about one or more servingfrequencies, or information about one or more serving bands) whereinformation cannot be received and sent in part of time when theterminal measures one or more measurement frequencies or measurementbands.

Optionally, when the information about the one or more serving cells (orthe information about the one or more serving frequencies, or theinformation about the one or more serving bands) where information canbe received and sent in part of time in the foregoing measurement gap isinformation about all current serving cells (or the information aboutthe one or more serving frequencies, or the information about the one ormore serving bands), the information about the one or more serving cellsmay be identified by “all”, and the information about all the currentserving cells (or the information about the one or more servingfrequencies, or the information about the one or more serving bands) isnot listed.

Optionally, the measurement gap parameter further includes a measurementgap pattern identity. The measurement gap pattern identity is associatedwith the foregoing plurality of parameters.

For example, mapping relationships are shown in Table 1.

TABLE 1 Measurement gap Measurement Information is normally pattern 1frequency received and sent in a (Period: 40 ms; (or band) 1 currentserving cell 1 (or length: 6 ms) at a serving frequency 1, or in aserving band 1). Measurement gap Measurement Information is normallypattern 2 frequency received and sent in a (Period: 80 ms; (or band) 2current serving cell 1 (or length: 6 ms) at a serving frequency 1, or ina serving band 1). Information is normally received and sent in acurrent serving cell 2 (or at a serving frequency 2, or in a servingband 2). Measurement gap Measurement Information is normally pattern 3frequency received and sent in a (Period: 40 ms; (or band) 3 currentserving cell 1 (or length: 4 ms) at a serving frequency 1, or in aserving band 1) in part of time.

S1520. The RAN device sends the measurement gap configuration parameterto a terminal.

Specifically, the measurement gap configuration parameter is included ina radio resource control (RRC) message.

According to this embodiment of this application, when the terminalmeasures different frequencies or bands, information can still bereceived and sent in the one or more current serving cells. Thisincreases a time of communication between the terminal and the RANdevice, and improves a data rate of the terminal.

Correspondingly, an embodiment of this application further provides aRAN device, including units configured to perform the method steps shownin FIG. 15. Implementation of the units is the same as described in theforegoing embodiments. The units may be implemented by using a processorto invoke a program stored in a memory, or may be integrated into one ormore integrated circuits or chips for implementation. In addition, for astructure of the RAN device, refer to FIG. 14.

Another embodiment of this application provides a method for configuringa measurement gap parameter. The method is used on a terminal. In otherwords, the method is performed by the terminal. The method includes thefollowing steps.

S1610. The terminal receives a measurement gap configuration parameter.

The measurement gap configuration parameter includes at least thefollowing:

information about one or more measurement frequencies or measurementbands;

information about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information can be normally received and sent when theterminal measures one or more measurement frequencies or measurementbands, namely, information receiving and sending cannot be performed inother serving cells (or serving frequencies or serving bands); orinformation about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information cannot be normally received and sent when theterminal measures one or more measurement frequencies or measurementbands; and

measurement gap pattern information, for example, a measurement gapperiod and a measurement gap offset, where optionally, the measurementgap pattern information further includes measurement gap lengthinformation (for example, 6 ms, 4 ms, or 3 ms).

Optionally, the foregoing measurement gap parameter further includesinformation about one or more serving cells (or information about one ormore serving frequencies, or information about one or more servingbands) where information can be received and sent in part of time whenthe terminal measures one or more measurement frequencies or measurementbands. That information can be received and sent in part of time meansthat: the terminal can receive and send information in the one or morecurrent serving cells (or at the one or more serving frequencies, or inthe one or more serving bands) within a measurement period, except for atime period needed for the terminal to adjust a radio frequency from afrequency corresponding to the information about the one or more currentserving cells (or the information about the one or more servingfrequencies, or the information about the one or more serving bands) toa frequency at which the one or more measurement frequencies ormeasurement bands can be measured, and except for a time period neededfor the terminal to adjust a radio frequency from a frequency at whichthe one or more measurement frequencies or measurement bands can bemeasured to a frequency corresponding to the information about the oneor more current serving cells (or the information about the one or moreserving frequencies, or the information about the one or more servingbands). For example, according to measurement gap parameter information,the terminal needs to measure a frequency f1 during moments 0 to 5, andthe terminal currently works at a frequency of f2. It is assumed thatthe terminal needs to take 1 ms to adjust a radio frequency from f2 to afrequency at which f1 can be measured, and the terminal needs to take 1ms to adjust the radio frequency from the frequency at which f1 can bemeasured back to f2. Therefore, a time during which the terminal canreceive and send information at f1 are moments 1 to 4. Alternatively,the foregoing measurement gap parameter includes information about oneor more serving cells (or information about one or more servingfrequencies, or information about one or more serving bands) whereinformation cannot be received and sent in part of time when theterminal measures one or more measurement frequencies or measurementbands.

Optionally, when the information about the one or more serving cells (orthe information about the one or more serving frequencies, or theinformation about the one or more serving bands) where information canbe received and sent in part of time in the foregoing measurement gap isinformation about all current serving cells (or the information aboutthe one or more serving frequencies, or the information about the one ormore serving bands), the information about the one or more serving cellsmay be identified by “all”, and the information about all the currentserving cells (or the information about the one or more servingfrequencies, or the information about the one or more serving bands) isnot listed.

Optionally, the measurement gap parameter further includes a measurementgap pattern identity. The measurement gap pattern identity is associatedwith the foregoing plurality of parameters.

For example, mapping relationships are shown below.

Measurement gap Measurement Information is normally pattern 1 frequencyreceived and sent in a (Period: 40 ms; (or band) 1 current serving cell1 (or length: 6 ms) at a serving frequency 1, or in a serving band 1).Measurement gap Measurement Information is normally pattern 2 frequencyreceived and sent in a (Period: 80 ms; (or band) 2 current serving cell1 (or length: 6 ms) at a serving frequency 1, or in a serving band 1).Information is normally received and sent in a current serving cell 2(or at a serving frequency 2, or in a serving band 2). Measurement gapMeasurement Information is normally pattern 3 frequency received andsent in a (Period: 40 ms; (or band) 3 current serving cell 1 (or length:4 ms) at a serving frequency 1, or in a serving band 1) in part of time.

Specifically, the measurement gap configuration parameter is included ina radio resource control (RRC) message.

S1620. The terminal performs measurement by using the measurement gapconfiguration parameter.

According to this embodiment of this application, when the terminalmeasures different frequencies or bands, information can still bereceived and sent on the one or more current serving cells. Thisincreases a time of communication between the terminal and the RANdevice, and improves a data rate of the terminal.

Correspondingly, an embodiment of this application further provides aterminal, including units configured to perform the method steps shownin FIG. 16. Implementation of the units is the same as described in theforegoing embodiments. The units may be implemented by using a processorto invoke a program stored in a memory, or may be integrated into one ormore integrated circuits or chips for implementation. In addition, for astructure of the terminal, refer to FIG. 13.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the present inventionbut not for limiting the present invention. Although the presentinvention is described in detail with reference to the foregoingembodiments, persons of ordinary skill in the art should understand thatthey may still make modifications to the technical solutions describedin the foregoing embodiments or make equivalent replacements to sometechnical features thereof, without departing from the spirit and scopeof the technical solutions of the embodiments of the present invention.

What is claimed is:
 1. A data processing method by a data sendingapparatus, comprising: receiving, at a Radio Link Control (RLC) layer, adata packet from a Packet Data Convergence Protocol (PDCP) layer,wherein the data packet is used as a first RLC service data unit (SDU);and encapsulating, at the RLC layer, the first RLC SDU into at least oneRLC protocol data unit (PDU), wherein each one of the at least one RLCPDU comprises: a header, and a payload carrying data from the first RLCSDU, wherein the at least one RLC PDU comprises a first RLC PDU and asecond RLC PDU, wherein the header of the first RLC PDU comprises asegment indicator (SI) field with two bits, wherein a first value of thetwo bits of the SI field in the header of the first RLC PDU indicatesthat the payload of the first RLC PDU comprises a first segment of thefirst RLC SDU, wherein the payload of the first RLC PDU comprises thefirst segment of the first RLC SDU, wherein the header of the second RLCPDU comprises: an SI field with two bits, and a segment offset (SO)field, wherein a second value of the two bits of the SI field in theheader of the second RLC PDU indicates that the payload of the secondRLC PDU comprises a last segment of the first RLC SDU, wherein thepayload of the second RLC PDU comprises the last segment of the firstRLC SDU, and wherein an offset value in the SO field in the header ofthe second RLC PDU indicates a byte offset within the first RLC SDUcorresponding to the first byte in the payload of the second RLC PDU. 2.The method according to claim 1, wherein the header of the first RLC PDUcomprises a sequence number (SN) field, the header of the second RLC PDUcomprises a SN field, and the SN fields of the first RLC PDU and thesecond RLC PDU carry a same SN.
 3. The method according to claim 1,wherein the encapsulating the first RLC SDU into at least one RLC PDUcomprises: encapsulating the first RLC SDU into the at least one RLC PDUbased on an indication from a Media Access Control (MAC) layer.
 4. Themethod according to claim 1, further comprising: receiving feedback froma data receiving apparatus that a transmitted RLC PDU is not correctlyreceived, and in response to the receiving feedback: further segmenting,at the RLC layer, the payload in the transmitted RLC PDU into aplurality of RLC PDUs, and retransmitting the payload in the pluralityof RLC PDUs.
 5. The method according to claim 1, wherein the datasending apparatus maintains, at the PDCP layer, a PDCP transmit window,and wherein the method further comprises: sending, at the PDCP layer bythe data sending apparatus, PDCP PDUs to the RLC layer; and stopping, bythe data sending apparatus, sending another PDCP PDU to the RLC layer inresponse to a quantity of the sent PDCP PDUs reaching a maximum quantityof PDCP PDUs that can be accommodated by the PDCP transmit window andnot receiving a successful feedback at the PDCP layer.
 6. The methodaccording to claim 1, wherein the at least one RLC PDU further comprisesa third RLC PDU, and the header of the third RLC PDU comprises an SIfield with two bits and an SO field, the SI field, in the header of thethird RLC PDU, has a third value indicating that the payload of thethird RLC PDU comprises a middle segment of the first RLC SDU, and thepayload of the third RLC PDU comprises the middle segment of the firstRLC SDU; and the SO field, in the header of the third RLC PDU, indicatesa byte offset, of a first byte in the payload of the third RLC PDU,within the first RLC SDU.
 7. The method according to claim 6, whereinthe header of each of the first RLC PDU, the second RLC PDU, and thethird RLC PDU comprises an SN field, and the SN fields of the first RLCPDU the second RLC PDU, and the third RLC PDU carry a same SN.
 8. Themethod according to claim 1, further comprising: receiving, at the RLClayer, another data packet from the PDCP layer, wherein the another datapacket is used as a second RLC SDU; encapsulating, at the RLC layer, thesecond RLC SDU into a fourth RLC PDU, wherein the fourth RLC PDUcomprises a header and a payload, the header of the fourth RLC PDUcomprises an SI field with two bits, the SI field, in the header of thefourth RLC PDU, has a fourth value indicating that the payload of thefourth RLC PDU comprises the complete second RLC SDU, and the payload ofthe fourth RLC PDU comprises the complete second RLC SDU.
 9. The methodaccording to claim 8, wherein the header of the fourth RLC PDU comprisesan SN field or no SN field.
 10. An apparatus, comprising a processor,configured to connect with a non-transitory computer readable medium,wherein the non-transitory computer readable medium storescomputer-executable instructions that, when executed by the processor,facilitate the apparatus performing a method comprising: receiving, atan Radio Link Control (RLC) layer, a data packet from a Packet DataConvergence Protocol (PDCP) layer, wherein the data packet is used as afirst RLC service data unit (SDU); and encapsulating, at the RLC layer,the first RLC SDU into at least one RLC protocol data unit (PDU),wherein each one of the at least one RLC PDU comprises: a header, and apayload carrying data from the first RLC SDU, wherein the at least oneRLC PDU comprises a first RLC PDU and a second RLC PDU, wherein theheader of the first RLC PDU comprises a segment indicator (SI) fieldwith two bits, wherein a first value of the two bits of the SI field inthe header of the first RLC PDU indicates that the payload of the firstRLC PDU comprises a first segment of the first RLC SDU, wherein thepayload of the first RLC PDU comprises the first segment of the firstRLC SDU; wherein the header of the second RLC PDU comprises: an SI fieldwith two bits, and a segment offset (SO) field, wherein a second valueof the two bits of the SI field in the header of the second RLC PDUindicates that the payload of the second RLC PDU comprises a lastsegment of the first RLC SDU, wherein the payload of the second RLC PDUcomprises the last segment of the first RLC SDU, and wherein an offsetvalue in the SO field in the header of the second RLC PDU indicates abyte offset within the first RLC SDU corresponding to the first byte inthe payload of the second RLC PDU.
 11. The apparatus according to claim10, wherein the header of the first RLC PDU comprises a sequence number(SN) field, and the header of the second RLC PDU comprises a SN field,and an SN in the SN field of the first RLC PDU is the same as an SN inthe SN field in the second RLC PDU.
 12. The apparatus according to claim10, wherein the encapsulating the first RLC SDU into at least one RLCPDU comprises: encapsulating the first RLC SDU into the at least one RLCPDU based on an indication from a Media Access Control (MAC) layer. 13.The apparatus according to claim 10, wherein the method facilitated byexecution of the computer-executable instructions by the processorfurther comprises: receiving feedback from a data receiving apparatusthat a transmitted RLC PDU is not correctly received, and in response tothe receiving feedback: further segmenting, at the RLC layer, thepayload in the transmitted RLC PDU into a plurality of RLC PDUs, andretransmitting the payload in the plurality of RLC PDUs.
 14. Theapparatus according to claim 10, wherein a PDCP transmit window ismaintained at the PDCP layer, and wherein the method facilitated byexecution of the computer-executable instructions by the processorfurther comprises: sending, at the PDCP layer, PDCP PDUs to the RLClayer; and stopping sending another PDCP PDU to the RLC layer inresponse to a quantity of the sent PDCP PDUs reaching a maximum quantityof PDCP PDUs that can be accommodated by the PDCP transmit window andnot receiving a successful feedback at the PDCP layer.
 15. The apparatusaccording to claim 10, wherein the at least one RLC PDU furthercomprises a third RLC PDU, and the header of the third RLC PDU comprisesan SI field with two bits and an SO field, the SI field, in the headerof the third RLC PDU, has a third value indicating that the payload ofthe third RLC PDU comprises a middle segment of the first RLC SDU, andthe payload of the third RLC PDU comprises the middle segment of thefirst RLC SDU; and the SO field, in the header of the third RLC PDU,indicates a byte offset, of a first byte in the payload of the third RLCPDU, within the first RLC SDU.
 16. The apparatus according to claim 15,wherein the header of each of the first RLC PDU, the second RLC PDU, andthe third RLC PDU comprises an SN field, and the SN fields of the firstRLC PDU the second RLC PDU, and the third RLC PDU carry a same SN. 17.The apparatus according to claim 10, the method facilitated by executionof the computer-executable instructions by the processor furthercomprises: receiving, at the RLC layer, another data packet from thePDCP layer, wherein the another data packet is used as a second RLC SDU;encapsulating, at the RLC layer, the second RLC SDU into a fourth RLCPDU, wherein the fourth RLC PDU comprises a header and a payload, theheader of the fourth RLC PDU comprises an SI field with two bits, the SIfield, in the header of the fourth RLC PDU, has a fourth valueindicating that the payload of the fourth RLC PDU comprises the completesecond RLC SDU, and the payload of the fourth RLC PDU comprises thecomplete second RLC SDU.
 18. The apparatus according to claim 17,wherein the header of the fourth RLC PDU comprises an SN field or no SNfield.
 19. A non-transitory computer readable storage medium comprisingcomputer-executable instructions such that, when executed by aprocessor, facilitate performing a method comprising: receiving, at anRadio Link Control (RLC) layer, a data packet from a Packet DataConvergence Protocol (PDCP) layer, wherein the data packet is used as afirst RLC service data unit (SDU); and encapsulating, at the RLC layer,the first RLC SDU into at least one RLC protocol data unit (PDU),wherein each one of the at least one RLC PDU comprises: a header, and apayload carrying data from the first RLC SDU, wherein the at least oneRLC PDU comprises a first RLC PDU and a second RLC PDU, wherein theheader of the first RLC PDU comprises a segment indicator (SI) fieldwith two bits, wherein a first value of the two bits of the SI field inthe header of the first RLC PDU indicates that the payload of the firstRLC PDU comprises a first segment of the first RLC SDU, wherein thepayload of the first RLC PDU comprises the first segment of the firstRLC SDU, wherein the header of the second RLC PDU comprises: an SI fieldwith two bits, and a segment offset (SO) field, wherein a second valueof the two bits of the SI field in the header of the second RLC PDUindicates that the payload of the second RLC PDU comprises a lastsegment of the first RLC SDU, wherein the payload of the second RLC PDUcomprises the last segment of the first RLC SDU, and wherein an offsetvalue in the SO field in the header of the second RLC PDU indicates abyte offset within the first RLC SDU corresponding to the first byte inthe payload of the second RLC PDU the payload carries data from a singleRLC SDU.